Resting-state fMRI in mice became a popular method to investigate brain circuits. However, uncertainty resides over the dynamic effects of anesthetics on brain states and functional connectivity. Using a multimodal approach with optical calcium recordings and RS-fMRI, we assessed brain states and networks while switching anesthetic regimen from 1% isoflurane to a combined 0.2% isoflurane/medetomidine anesthesia. We find that brain states reach a steady state after a short transition time and detected that functional connectivity changes were strongest relative to the 1% isoflurane condition. We conclude that brain states and networks are stable from 30 minutes after switching anesthetic regimen.